Large methane releases lead to strong aerosol forcing and reduced cloudiness

Publication: Research - peer-reviewJournal article – Annual report year: 2011



  • Author: Kurten, T.

    University of Helsinki

  • Author: Zhou, L.

    University of Helsinki

  • Author: Makkonen, R.

    University of Helsinki

  • Author: Merikanto, J.

    University of Helsinki

  • Author: Raisanen, P.

    Finnish Meteorological Institute

  • Author: Boy, M.

    University of Helsinki

  • Author: Richards, N.

    University of Leeds

  • Author: Rap, A.

    University of Leeds

  • Author: Smolander, S.

    University of Helsinki

  • Author: Sogachev, Andrey

    Meteorology, Wind Energy Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Denmark

  • Author: Guenther, A.

    National Center for Atmospheric Research

  • Author: Mann, G. W.

    University of Leeds

  • Author: Carslaw, K.

    University of Leeds

  • Author: Kulmala, M.

    University of Helsinki

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The release of vast quantities of methane into the atmosphere as a result of clathrate destabilization is a potential mechanism for rapid amplification of global warming. Previous studies have calculated the enhanced warming based mainly on the radiative effect of the methane itself, with smaller contributions from the associated carbon dioxide or ozone increases. Here, we study the effect of strongly elevated methane (CH4) levels on oxidant and aerosol particle concentrations using a combination of chemistry-transport and general circulation models. A 10-fold increase in methane concentrations is predicted to significantly decrease hydroxyl radical (OH) concentrations, while moderately increasing ozone (O-3). These changes lead to a 70% increase in the atmospheric lifetime of methane, and an 18% decrease in global mean cloud droplet number concentrations (CDNC). The CDNC change causes a radiative forcing that is comparable in magnitude to the long-wave radiative forcing ("enhanced greenhouse effect") of the added methane. Together, the indirect CH4-O-3 and CH4-OHaerosol forcings could more than double the warming effect of large methane increases. Our findings may help explain the anomalously large temperature changes associated with historic methane releases.
Original languageEnglish
JournalAtmospheric Chemistry and Physics
Issue number14
Pages (from-to)6961-6969
StatePublished - 2011

Bibliographical note

This work is distributed under the Creative Commons Attribution 3.0 License.

CitationsWeb of Science® Times Cited: 9


  • Wind power meteorology
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